Currently, existing capacitive in-cell touch screens include a mutually capacitive touch screen and a self capacitive touch screen. For the self capacitive touch screen, a layer of touch electrodes may be arranged in the touch screen, and a driving signal is applied to each touch electrode. When no touch has been made, a capacitance of the touch electrode is of a constant value a, and when the touch has been made by a finger, the resultant capacitance is a sum of a capacitance of the finger and the original capacitance a. By detecting a change in the capacitance of the touch electrode, it is able to determine a position where the touch is made.